Twenty-six properties, including bed and breakfast accommodation, were flooded in the coastal town, causing hundreds of thousands of pounds damage, as drains in the street overflowed.

More than 2in (50mm) of rain fell in a 12-hour downpour overnight on Sunday in places along the south coast, which also left low-lying parts of Worthing Hospital knee-deep in dirty water.

Emergency patients had to be diverted to hospitals in Brighton and Chichester overnight as a 1ft of water flooded several buildings.

Children were sent home after schools in Bosham, near Chichester, West Sussex, and Bracknell, Berks, were flooded and closed their doors.

Firefighters had to be called to dam up a torrent of water flooding down a hill towards a school in Cosham, Hants, using sandbags after classrooms were evaucated.

Standing water also caused several roads to be closed including a section of the A33 near Basingstoke, Hants, the A27 between Chichester and Portsmouth, and the M1 near Leeds.

A man had to be rescued by firefighters after his car got stuck in a ford in Waterlooville, Hampshire, and started taking in water running off from nearby fields. The driver was pulled out of his vehicle shortly before midday as water filled his car up to seat level.

The Met Office issued a severe weather warning covering London and the south east amid concerns over treacherous driving conditions and flood risks.

Forecasters said the soggy start to the summer was just a taste of the washout in store for the rest of June with more heavy downpours expected at times throughout the next two weeks and beyond.

After another deluge overnight, the rain is likely to ease slightly through today and tomorrow before a return to heavy showers on Thursday and Friday.

Long range forecasts suggest there may be more rain over the weekend with unsettled conditions likely to continue for the rest of the month.

Firefighters in West Sussex received more than 80 flood-related calls between 10.30pm yesterday and 3am.

The Environment Agency issued two flood warnings – the second most serious category – for the Rover Mole at Charlwood and Hookwood, and at Sidlow, Leigh and Betchworth, saying homes are at risk from rising water.

The agency also issued 38 flood alerts as rivers near bursting point – 35 of them for the south east region.

The flooding follows the evacuation of the village of Pennal, near Machynlleth, Powys, north Wales, at the weekend after heavy downpours led to fears of a breach in the dam of a disused quarry.

More than 600 people had to be taken to safety from the village after a crack was found in a wall and water began escaping from the reservoir.

Families were allowed to return to their homes today after firefighters managed to ease pressure on the dam by carrying out two controlled releases of water.

Some 150 people were also rescued from homes and caravan parks near Aberystwyth on Saturday after twice as much rain fell in 24 hours as normally falls in the area in the whole of June.

A number of rivers burst their banks as the stormwater flowed downstream with Talybont, Dol-y-bont, Llandre, and Penrhyncoch among those worst affected, with flood water rising to 5ft (1.5m) in some places.